Its a LOT different here in Canada! You have no recourse at all. But on the bright side you did find it in time to correct the problem before it became huge.
I would think that the moisture most likely came from 1 or 2 different areas.
First off some warm air would have gotten into the insulation threw the wall sockets in the kitchen. When that warm air hit the cold air coming into the wall cavity from your garage it would have caused some condensation. that would have gotten your insulation a bit wet which probably helped to create some of the mold.
To fix that from happening again buy a couple of those clear plastic box covers & put them around the kitchen outlet boxes (now that you have the wall opened) from the garage side. Seal them to the vapor barrier with tuck tape (the red stuff & don't be shy with it either). while your at it check the vapor barrier for any other openings & seal them with tuck tape as well.
Secondly by the looks of it, most of the moisture appears to be coming from the bottom. Combine that with the wet appearing drywall, makes me think that there was a lot of moisture coming from the garage side. Here in southern Ontario most homes built in the early 80's, when there was drywall put up in the garage, it stopped about a foot or so from the garage floor. Leaving the drywall with an open end exposed. If, as someone had suggested in an earlier post, washed their car in the garage, moisture would have easily gotten the lower part of the insulation wet. Again causing mold.
My suggestion would be for you to, after the vapor barrier repair & after you re insulate, would be to cover the wall in Ty Par/exterior building wrap. This stuff repels moisture but is still breathable. Then install mold resistant/paperless drywall (keeping it at the 1 foot off the floor height it was at). Next I would finish the garage drywall with a full 2 coats of mud, primer & a water resistant paint (a bathroom paint would work) And lastly I would cap the bottom of the drywall with some kind of trim, primed, painted & caulked around (top & bottom of the trim)
I tried to draw the trim finish with a paint program, hope you get what I mean.
black= foundation
red= garage floor
blue= drywall
green= 2x4 base plate
yellow= trim
pink= caulking
I am also in southern Ontario, PM me & if your close enough to me I would gladly give you a hand.
Steve